[Collins] 51J4 Crystal Filter

[Dr. Gerald N. Johnson]

But the tuning capacitor is shorted by the coil at least in T101 in the 
51J-4. So it has DC to ground, but not across the coil. And signal level 
at that point in the receiver isn't even going to be a few volts, else 
the crystal would fracture. And all the tuning capacitor sees is signal 
voltage.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 9/24/2011 8:55 PM, Carl wrote:
> Umm, the primary of an IF transformer has the tubes plate voltage.
>
> We are not discussing grid drive in a transmitter.
>
> Carl
> KM1H
> ----- Original Message ----- From: "Dr. Gerald N. Johnson"
> <geraldj at weather.net>
> To: "Carl" <km1h at jeremy.mv.com>
> Cc: <collins at mailman.qth.net>
> Sent: Saturday, September 24, 2011 7:04 PM
> Subject: Re: [Collins] 51J4 Crystal Filter
>
>
>> But they see only signal voltage, not DC. If they saw DC or PA grid
>> drive, they would not survive.
>>
>> 73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association
>>
>> On 9/24/2011 3:57 PM, Carl wrote:
>>> Those caps are rated at only 50V so dont do so well in the primary
>>> circuit of IF transformers.
>>>
>>> Carl
>>> KM1H
>>>
>>>